The MTA launched an ad campaign to convince riders not to use emergency exit gates unless there’s an actual emergency.

Police say they’ll ticket – or even arrest – riders who use the gates to allow other customers entry into the system, the ads warn.

Panic bars and alarms have been installed on the gates at all 468 stations so that large crowds can be evacuated quickly in the event of a terrorist attack or other disaster, replacing the locks and chains that were on the gates to keep out fare evaders .

But as The Post reported recently, the alarms are activated so often for non-emergencies – usually by riders in a rush – that they frequently break down.